1. Field of the Invention
This invention relates to a new and improved process and associated apparatus for recovery of hydrogen from lunar soil.
2. Brief Description of the Prior Art
The incentive for oxygen production on the moon is primarily the increased payload thereby made possible for other space missions which then do not have to carry all their propellant and life-support oxygen from earth. Also, oxygen produced on the moon requires much less launch energy and propellants to transport it to another space use, such as a space station, than oxygen launched from the deep gravity well of earth. An oxygen plant is therefore a key facility in a manned lunar base or colony.
In applicants' co-pending U.S. patent application Ser. No. 118,414, a process is shown and described for production of oxygen from lunar materials by reduction of iron-oxygen compounds with hydrogen. The process requires beneficiation and mineral separation steps upstream of the reduction reactor and chemical or physical techniques downstream to extract the oxygen and regenerate the reducing agents. The hydrogen used in the initial operation of the process is transported from earth. However, for extended operation, the process is more practical if it can utilize hydrogen recovered from lunar materials.
The presence of hydrogen in lunar soil was expected on theoretical grounds, even before the first manned lunar landings. It was known that the energy emitted by the sun includes protons (positively charged hydrogen nuclei) in the form of a "solar wind". In the several billion year history of the solar system, the protons emitted by the sun must have collected, in part, in the soil or surface materials of the moon. The actual presence of hydrogen in lunar materials was detected early in the lunar exploration programs.
Epstein S. and Taylor H. P., Jr. (1970) Proc. Apollo 11 Sci. Conf. 1085-1096 reports the concentration and isotopic composition of hydrogen, carbon and silicon in Apollo 11 lunar rocks and minerals. Chang S., Lennon K., and Gibson E. K., Jr. (1974) Proc. Lunar Sci. Conf. 5th, 1785-1800 reports Abundances of C, N, H, He, and S in Apollo 17 soils from Stations 3 and 4: Implications for solar wind exposure ages and regolith evolution. Carr R. H., Bustin, and Gibson, E. K., Jr. (1986) submitted to Analytic Chemistry reports the determination of hydrogen in lunar soils by pyrolysis--gas chromatography. Bustin R., (1986) in a final report prepared for Northrop Services, Inc. reports on hydrogen abundance in lunar soils. Bustin (1986) also reports the yields of other species desorbed with the hydrogen, viz., helium, nitrogen and carbon oxides. A report by Wittenberg, L. J. (1986) and others at the University of Wisconsin Fusion Technology Institute, Fusion Technology 10 (2), September 1986, points out that the lunar helium is much richer in isotope weight 3, a desirable fusion reactor fuel, than terrestial helium. Consequently, the separation and purification of .sup.3 He and possibly other byproducts from the main hydrogen product may be attractive.
The literature relating to analysis of lunar soil samples and minerals reports appreciable amounts of hydrogen in the surface soils but offers no suggestion as to the practicality of recovering hydrogen or the process or apparatus which might be required for hydrogen recovery.